dt-bindings: mmc: sdhci-of-arasan: Add new compatible for AM654 MMC PHY

Add a new compatible to use the host controller driver with the
MMC PHY on TI's AM654 SOCs

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>